Diseases of the cardiovascular system affect millions of people each year and are a leading cause of death throughout the world. The cost to society from such diseases is enormous both in terms of the number of lives lost as well as in terms of the costs associated with treating patients through traditional surgical techniques. A particularly prevalent form of cardiovascular disease is a reduction in the blood supply leading to the heart caused by atherosclerosis or other condition that creates a restriction in blood flow at a critical point in the cardiovascular system that supplies blood to the heart.
Treatment of such a blockage or restriction in the blood flow leading to the heart is, in many cases, treated by a surgical procedure known as a coronary artery bypass graft (CABG) procedure, more commonly known as a "heart bypass" operation. In the CABG procedure, the surgeon "bypasses" the obstruction to restore normal blood flow to the heart either by attaching an available source vessel to the obstructed target coronary artery or by removing a portion of a vein or artery from another part of the body, to use as a graft, and installing the graft between a point on a source vessel and a point on a target artery.
To restore the flow of blood to the heart, the CABG procedure requires that a fluid connection be established between two vessels. This procedure is known as an "anastomosis." Typically, a source vessel, such as a source artery with an unobstructed blood flow, i.e., the left internal mammary artery (LIMA), or a bypass-graft having one end sewn to an unobstructed blood source such as the aorta, is sewn to a target occluded coronary artery, such as the left anterior descending (LAD) artery or other vessel, that provides blood flow to the muscles of the heart.
Although the CABG procedure has become relatively common, the procedure itself is lengthy and traumatic and can damage the heart, the cardiovascular system, the central nervous system, and the blood supply itself. In a conventional CABG procedure, the surgeon makes an incision down the center of the chest, cuts through the sternum, performs several other procedures necessary to attach the patient to a heart-lung bypass machine, cuts off the blood flow to the heart, and then stops the heart from beating in order to complete the bypass. The most lengthy and traumatic surgical procedures are necessary, in part, to connect the patient to a cardiopulmonary bypass (CPB) machine to continue the circulation of oxygenated blood to the rest of the body while the bypass is completed.
In recent years, a growing number of surgeons have begun performing CABG procedures using surgical techniques especially developed so that the CABG procedure could be performed while the heart is still beating. In such procedures, there is no need for any form of cardiopulmonary bypass, no need to perform the extensive surgical procedures necessary to connect the patient to a cardiopulmonary bypass machine, and no need to stop the heart. As a result, these beating heart procedures are much less invasive and the entire procedure can typically be achieved through a small number, typically one or two, comparatively small incisions in the chest.
Despite the advantages, the beating-heart CABG procedure is not universally practiced, at least in part, because of the difficulty in performing the necessary surgical procedures using conventional surgical instruments. For example, it has been difficult for the surgeon to access the required areas of the heart requiring revascularization. In addition, the various surgical steps that are required to be performed on the heart itself are more difficult to perform because the heart muscle continues to move and contract to pump blood throughout the duration of the procedure.
The specific portion of the surgical procedure that creates the anastomosis in the beating-heart CABG procedure is particularly difficult. Completion of the anastomosis requires placing a series of sutures through extremely small vessels on the surface of the heart while the heart muscle continues to beat. Moreover, the sutures must be carefully placed to ensure that the source vessel or graft is firmly attached and will not leak when blood flow through the vessel is established. In cases where the target coronary artery is temporarily obstructed, for example, to improve the surgeon's visibility and avoid excessive blood loss, it is also important that the anastomosis procedure be performed rapidly to avoid ischemic damage to the heart.
Further adding to the difficulty of the procedure is the fact that the working space and visual access are often quite limited. The surgeon may be working through a small incision in the chest, for example, or may be viewing the procedure on a video monitor if the site of the surgery is viewed via surgical scope. The vessel, and particularly the arteriotomy to which a source vessel is to be anastomosed, may also be very difficult for the surgeon to see as it may be obscured more or less by layers of fat or other tissue.
The beating-heart CABG procedure could be greatly improved if the heart could be accessed and stabilized during the procedure such that the motion of the heart, particularly at the site of the anastomosis, is minimized even though the heart continues to beat and supply blood to the body. The beating-heart CABG procedure could be further improved if the target vessel, and specifically the arteriotomy was presented to the surgeon in a way that allows sutures to be easily placed.
In view of the foregoing, it would be desirable to have improved devices for accessing and effectively stabilizing the beating heart at the site of the anastomosis. It would be desirable to have a retractor system that provides unobstructed and organized access to the areas of the heart requiring revascularization. It would be further desirable to have a low-profile, atraumatic stabilizing device that stabilizes the beating heart at the site of the anastomosis and provides a favorable presentation of the target vessel and the arteriotomy. It would be further desirable to provide a mount for the stabilizing device, or other instruments, that allows the stabilizing device to be easily maneuvered to the desired position and orientation, fixedly secured until the procedure is completed, and then easily removed from the site of the anastomosis.